27. Gas Exchange1Full

27. Gas Exchange1Full - Gas Exchange Moving...

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Unformatted text preview: Gas Exchange: Moving molecules (Mostly O 2 ) BSCI 207: Organismal Biology BSCI 105 / BSCI 106 or AP Biology course Physics and phylogeny Evolutionary survey Design principles Form and function Organismal perspective www.vashonsd.wednet.edu/everest/itinerary.htm Each Fundamental Process of Life Universal physical and chemical principles Common genomic toolkit from LUCAC places design constraints on provides certain opportunities for provides molecular solutions for can evolve for Unity of Life Diversity of Life Ecological roles Organismal strategies Different cells, tissues, & organs selection pressures and/or 1. Big Steps in the Origin of Life • Origin of information processing/replication system • Origin of metabolism for generating small organic molecules and larger polymers • Origin of bioenergetics • Origin of lipid membranes defining the boundary of life – the challenge of impermeable membranes C & R 26.12 Gases - high permeability -> do not require transport proteins Nutrients - low permeability -> require selective transport proteins 2. Difference between Gas Exchange and Nutrient Assimilation - F. Fig. 6.8 3. Learning objectives - Unique gas exchange and circulatory systems in multicellular lineages 1. No specializations for gas exchange and circulation in unicellular organisms - passive diffusion only 2. Independent origins of gas exchange and/or circulatory systems in various multicellular animal and plant lineages 3. Physical constraints (Fick’s Law and Hagen-Poiseuille equation) operating on convergent structures Introduction - Diffusion in cells Diffusion works fine across membranes, organelles, and most cells In general, no need to evolve special mechanisms for facilitating the movement of most molecules via diffusion over short distances. ( Exception : the challenge of membrane permeability for most large, charged, and/or polar molecules) Introduction - Ventilatory and circulatory systems in animals – more in later lectures! F Fig. 44.11 Ventilation • Bulk flow/convection of medium (air) • Diffusion of O 2 and CO 2 across alveolar membranes arditobook.pbworks.com/The-Circulatory-System Circulation • Bulk flow/convection of medium (blood) • Diffusion of gases, food molecules, and waste products across capillary membranes Gas exchange – Unity of Life Fick’s Law Common physics expression Flux = per unit area of an organ Alternative biological expression Flow = total capacity of an organ...
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This note was uploaded on 04/05/2012 for the course BSCI 207 taught by Professor Higgins during the Spring '08 term at Maryland.

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27. Gas Exchange1Full - Gas Exchange Moving...

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